Propeller governor



June 21, 1949. c. w. CHILLSON PROPELLER GOVERNOR Original Filed March 15. 1939 4 1 mvamon Camus Mammy ATTORNEY June 1949- c. w. CHILLSON 74,140

PROPELLER GOVERNOR Original Filed March 15. 1939 4 Sheets-Sheet 2 INVENTOR CHHRLBS MMLLSON Mme! ATTORNEY 4 21, 1949. c:. w. CHILLSON 2,474,140

PROPELLER GOVERNOR ori inal Filed larch 1'5. 1939 4 Shee'ts-Sheet 3 FIE. E1

INV ENTOR 6224mm Wmmwmw ATTORNEY June 21, 1949. c. w. 'CHILLSON PROPELLER GOVERNOR Original Filed larch 15. 1939' 4 Sheets-Sheet 4 w 7 5 a 9 7 1 a a 1 1 m m 5 01- EPEM LJOIV ATTORNEY Patented June 21, 1949 PROPELLER GOVERNOR Charles w. Chillson, Caldwell, N. J., assignor to Curtiss-Wright'Col-poration, a corporation of Delaware Continuation of application Serial No.

October 8, 1940, which is a division of application Serial No. 261,879, March 15, 1939.

This

application February 14, 1946, Serial No. 647,634

4 Claims. (Cl. 200-53) This invention relates to control and governing mechanisms for controllable pitch aircraft propellers, the particular embodiment of the invention chosen for illustration being applicable to electrically operated controllable pitch propellers of the type disclosed in Patent No. 1,951,320, is-

sued March 13, 1934, to W. J. Blanchard.

This application is a continuation of application Serial No. 360,243, filed October 8, 1940, which was a division of application Serial No;

261,879, filed March 15, 1939, and which has since become Patent No. 2,449,452.

Controllable pitch propellers are now being provided with a governor by which pitch settings of the propeller are increased or decreased in response to tendencies of the engine to gain or lose R, P. M. from a preset standard. whereby the propeller maintains constant speed at any desired setting 01 the governor.

An inherent characteristic of a speed regulating system such as the constant speed governor, controllable-pitch-propeller, airplane-engine combination where the rate of pitch change is essentially constant regardless of the magnitude of the pitch correction being made, and where there is an appreciable time lag between the application of the correction and the responses of the propeller due to engine and propeller inertia, is that for a given substantially constant rate of correction and a definite time lag relationship, there will be a definite maximum governor sensitivity which the system will tolerate without developing hunting characteristics.

With the growing need for rapid pitch change to prevent over and under speeding with rapid throttle changes or abrupt changes in flight regime, combined with the importance of synchronizing engines closely on multi-motor installations, it has become desirable to provide some means for speed control other than asimple single sensitivity governor. For this reason, a proportional type of control has been developed which supplies pitch corrections in response to speed variations in increments, the magnitude of which is proportional to the speed variation. This not only provides a closer speed control but permits the use of a higher basic rate of pitch change without causing hunting.

An object oi! this invention is to provide a governing mechanism for a controllable pitch propeller which shall produce pitch change impulses of varying dwell according to the pitch deviation from the desideratum, the impulses shortening as the pitch approaches the desired value.

A further object is to provide such a governor 2 arrangement particularly applicable to propellers whose pitch is controlled electrically.

Another object of the invention is to provide a governor mechanism whose control action may be transmitted intermittently to the propeller control motor, the dwell of the intermittent pitch changing impulses decreasing as the propeller approaches the desired pitch setting.

Still another object is to provide a governing mechanism which will operate automatically to effect either increase or decrease in propeller blade pitch.

Additional objects comprise the use of a hydraulically controlled electric governor unit and the provision of a hydraulic pressure responsive switch controlling propeller response to the governor, whereby failure of hydraulic pressure will lock the propeller in fixed pitch in or at normal operating range.

Further objects of the invention comprise the particular construction of a governor mechanism, the features of which will be pointed out in the annexed detail description in connection with the drawings, in which:

Fig. 1 is an elevation of a part of a controllable pitch propeller as mounted upon an engine nose, the latter being partly in section to show the propeller governor drive;

Fig. 2 is a wiring diagram of the electrical circuit involved in the system;

Fig. 3 is an enlarged elevation of the propeller governor in the same aspect as is shown in Fig. 1, partly broken away and partly in section, to show certain of the details of construction;

Fig. 4 is a plan section, broken away in part, of the governor;

Figs. 5, 6 and 7 are sections, respectively, on the lines 55, 6-6 and 1-1 of Fig. 4;

Fig. 8 is a plan of the governor, and

Fig. 9 is an enlarged detail section through a portion of the governor mechanism.

Reference may first be made to Fig. 1, in which l0 designates a propeller hub carrying blades II mounted 'for pitch changing rotation and carrying a power unit 12, the latter comprising an electric motor l3 and speed reducers l4 and I5 connected by gears, not shown, to the blade roots. The elements III to I5, inclusive, along with a slip ring assembly I 6, are generally similar to the propeller mechanism shown in said Patent No. 1,951,320. The propeller is mounted upon an engine propeller shaft carried in part by an engine nose section H which incorporates a mounting pad I8 for a governor shown in its entirety as 19. This governor has a driving connection 20 with a shaft 2i driven through an integral bevel gear 22 from a bevel gear 23 carried on a rotating part 23 of the engine which, as shown, comprises a part of the cam and valve gear system. The engine pressure oiling system provides part of the operating power for the governor in a manner hereafter to be described, pressure oil being led through a conduit 23 in the nose section to the governor mounting pad I 3.

Fig. 2 shows the wiring system for the propeller, the dot-dash line block 23 representing the propeller power unit embodying the motor rotor 21, and pitch increasing and pitch decreasing field windings 28 and 29, respectively. The block l3 represents the slip ring assembly. A power source 30 is provided; and blocks 3| and l 3 represent a manual control unit and the automatic control unit. Connections from the manual control unit 3| to the propeller are conventional in character, the control unit having a master switch 32 contactible with a switch point 33 to place the circuit in readiness for selective pitch increase or decrease through the switch 33. The switch 32 may also be engaged with the point 33 which disconnects the manual selective control and places the governor unit l3 in circuit, this circuit including a switch 33 responsive, as will be described hereafter, to oil pressure and consequently to engine operation. The unit also includes an oscillatable switch arm 31 contactible with switch point 33 or 39 to decrease or increase propeller pitch respectively, the switch unit 31-33-39 being governor controlled, as will become apparent.

Reference may now be made to Figs. 3 to 9, which show the details of construction of the governor l9. Referring particularly to Fig. 7, it will be seen that the governor driving connection 20 comprises a sleeve 3i rotatable in a bushing 42, the sleeve terminating in a governor plate 33 on which flyweights 33 are pivoted at 35, the flyweights being connected to a ring 33 secured to the outer race of a ball thrust bearing 31, the inner race of which is secured by the nut 33 to a valve stem 39. I'he vertical position of the valve stem is accordingly controlled by the position of the flyweights 33 which, of course, makes the vertical position oi. the valve stem speed responsive. A spring 33 counteracts radial displacement due to centrifugal force in the flyweights 33 and the force imposed by the spring upon the governor is adjustable by turning a lever 3i mounted on a shaft 52 having an integral pinion meshing with a rack 53 which forms the top abutment for the spring 53. This adjustment is mounted in a housing 54 which forms a cover for the governor.

The pressure oil conduit 23 previously referred to terminates adjacent the mounting pad on the engine and registers with a segmental groove 53 (Fig. 7) at the mounting face of the governor, drillings leading therefrom to a safety switch cavity 51 through a drilling 33. Another drilling 59 leads from the groove 33 to the upper part of the bushing 32 through a hole in which the oil may pass to an annulus 33 formed in the sleeve 3| driven by the element". This sleeve has a drilling 33 through which oil may pass to an annular groove 33 in the valve stem 33 when the latter is raised by the governor flyweights. 011 may flow through the annular groove to lower radial drillings 33 in the sleeve 3| which communicate with a set of passages 31 leading to a cylinder 33 having therein a spring-pressed piston 39, the stem or which is borne in a bushing 13 and extends into a switch box H to carry the switch arm 31 indicated in the wiring diagram and shown more clearly in Fig. 3. When the valve stem 49 assumes a low position due to low engine R. P. M., the opening 33 is covered and the annular groove of the valve stem may uncover the bore of the sleeve 3!, as at 13, to permit oil to bleed from the cylinder 33 to the engine crankcase. The stem and sleeve units 33 and 3i thereby comprise a governor controlled hydraulic valve which will control theposition of the switch arm piston 39 in accordance with engine R. P. M. as selected by adjustment of the governor spring control arm 3i. Any variations in engine speed will find response in the position of the valve stem 49 and thus in the position of the piston 33.

Referring now to Fig. 3, it will be seen that the stem of the piston 33, designated 13, is embraced by a spring 13 abutting at its ends upon slidable washers 13 and I1 abutting shoulders on a sleeve assembly 13, the washer I3 also abutting a lower shoulder on the stem 13 and the washer I'I abutting a cylindrical nut I3 screwed upon the stem 13 with respect to which the sleeve assembly 13 is slidable. By this construction, the spring 15 holds the sleeve 13 in a normally fixed position,

- but if the sleeve be positively reciprocated with respect to the valve stem I3, the spring provides a resilient centralizing force regardless of the direction of displacement of the sleeve. The sleeve 13, as is apparent, carries the switch arm 31 in insulated relation thereto, the arm being provided with appropriate contact pieces 33.

Mounted in the housing and projecting into the box Ii is a reciprocable plunger 32, as shown in Figs. 3 and 5, this plunger carrying the contacts 33 and 39 in insulated relation thereto and to each other through bushings 33 secured by a nut 34. The contact pieces 33 and 39 are engageable in a manner later to be described with the contacts 33. The plunger 32 carries, at its lower end, a roller 33, the plunger being reciprocable in a bushing 33 secured from rotation by a dowel 31 and anchored to the deck of the box H by a plate 33 and screws 89 (Fig. The plunger is prevented from rotating in the bushing 33 by the engagement of the roller pin 93 in a slot 3| in the bushing. The roller engages a cam 32, being spring-pressed toward the cam by a spring 93 within the bushing. Said cam is provided with a projecting lobe 93 anda depressed lobe 35, and is carried upon a shaft 93 journaled in the housing and having a worm wheel 9! driven by a worm 33 on the upper end of the shaft of which a pump gear 99 (Figs. 4, 5 and 6) is secured. The gear 99 meshes with a gear I 33 secured to the engine driven sleeve 3i the gears 99 and I33 comprising a scavenging oil pump, the nature of which will be described shortly. It will be apparent, however, that the camshaft 93 with its cam is driven by the sleeve 3i so that the plunger 32 is reciprocated up and down in proportion to engine speed. The dwell of the cam follower on the concentric portions of the cam holds the contact pieces 38 and 39 in. neutral position, whereas, when the cam follower rises on the lobe 93 and drops into the lobe 95, successive downward and upward movements are imparted to the contact carrying bushings 83. The general operation of the system will now become apparentcertain detailed structures have not yet been fully covered, but are necessary to the governor assembly, and will be pointed out hereafter.

Since the propeller pitch actuating motor i3 runs at constant speed when energized, it would 5 tend to produce a constant rate of pitch change that may be necessary. The intermittent action of the governor-has the effect of producing continuous energization of the propeller pitch motor when the pitch change to be made is large, but

has the eifect of intermittently energizing the motor when the pitch change to be made is small. The accomplishment of this function will be apparent when it is realized that the position of the contact points is always determined in response to engine R. P. M. and to the setting of the piston and from which 011 may flow through a drilling I23 in the housing, shown in Fig. 7, to the governor cavity. In Fig. passage I24 supplies lubricating oil to cam 02, gears 91 and lished by a proper balance of the governor, the

governor will change position and will either raise or lower-the contacts 00, whereupon one or the other of the reciprocating contacts 00 or 30 will intermittently engage contact 00 to intermittently energize the propeller pitch motor, to operate same for the purpose of altering the propeller pitch to re-establish the R. P.-M. balance. If the deviation from normal is pronounced, one of the contacts 80 may ride the contact 08 or 00 .throughout an entire reciprocative movement,

the spring I5 associated with the carrier oi the contacts 80 permitting oi this continual contact.

As propeller pitch approaches the desired pitch,-

the position of the contacts 00 will have been raised or lowered to shorten the contact time during reciprocations of the contacts 30 and 00 until finally, said contacts cease and the system again becomes balanced.

In Figs. '7 and 9 is shown the safety switch 30 which comprises a switch assembly inserted into a bore I05 in the governor housing, the two wires from the safety switch leading respectively through arm 31 to contacts 00 and to a junction plug I06. This'junction plug I00 also carries two additional wires leading to the contacts 38 and 39, being clipped to the bushing assembly 03 by clips I01 and I00. As shown in Figs. 7 and 9 the bottom part of the bore I05 terminates in the cavity 51 communicating with the oil pressure source, the switch comprising a piston I00 acted upon by pressure 011 to raise same. piston I09 carries an insulating bushing I I0 within which a ball III rests, the ball carrying a contact yoke II2 raisable withfthe piston. This piston is normally urged downwardly by a spring II3 enclosing an insulating sleeve Ill which in turn embraces contact bars II! and H6 axially located in the bushing I I by insulating pins I II, the bars being insulated from one another by a strip I I8. The lower ends of the bars IIS and I I6 are bridged by the element II2 so that when sufiicient oil pressure exists below the piston I00 the switch circuit is closed. When such pressure is relieved, the element II2 breaks the circuit of the switch. Oil relief from the switch is provided through a drilling I I9 by which leakage may flow to the governor cavity for subsequent drainage to the engine. The safety switch is preferably set to open the governor circuit when oil pressure drops below 15 to 20 lb. per sq. in. whereupon the propeller will assume a flxed pitch subject to change by the manual unit 3 I.

In connection with the piston and associated structure, said piston slides in the bushing 10 part of which is formed as a cylinder which is provided with holes I22 to receive oil bleed past The SI and associated journal bearings from surplus oil in the governor cavity. It also provides a pressure relief for the oil filled cam cavity against pressure fluctuations caused by the reciprocation of plunger 02.

Below the governor plate 40, referring to Figs. 4 and 6, the gears 99 and I00 are located, and the floor of the governor cavity is so formed in conjunction with a ring I26 as to provide a housing embracing the. gears 00 and I00 to permit them' to operate as a scavenging oil pump. Oil collecting in the governor cavity will enter the gear teeth, as shown by the arrows A, and will be carried around the gears to the point B, whereat a hole I2! is drilled in the ring I26 to permit scavenge oil to flow into a cavity I20 connecting with a drilling I29 in the housing which in turn discharges through a hole in the bushing 42 as at I30 whence the oil may pass through the hollow driving sleeve to the interior of the engine crankcase.

While I have described my invention in detail in its present preferred embodiment, it will be obvious to those skilled in the art, after understanding my invention, that various changes and modifications may be made therein without departing from the spirit or scope thereof. I aim in the appended claims to cover all such modifications and changes.

I claim:

1. In an engine hydro-electric governor device, a source of fluid derived from the engine, engine speed responsive means including a valve con-.

trolling said fluid, a fluid motor actuated by valve-controlled fluid, a switch point movable in response to motor actuation, a second switch point with which said first point is engageable, and engine driven means for periodically moving said second switch point toward and 'away from contact with said first switch point, said points being yieldable upon contact with one another to maintain contact for varying periods according to the position of said first switch point as controlled by said fluid motor.

2. In a hydro-electric speed control device for an engine, a source of fluid, a chamber, an engine speed responsive movable valve controlling the application of fluid to said chamber, a piston movable in said chamber, the position of said piston in the chamber being dependent on the amount of fluid therein as controlled by said valve, an electrical switch contact movable with said piston, a second switch contact engageable at times with the first, one of said contacts being resiliently mounted, and means for cyclically moving said second contact toward and away from the flrst contact to effect, at times, intermittent engagements of said contacts, the dura-- tion of said engagements depending on the position of said piston and first contact and the cyclic rate of said second contact.

3. In a hydro-electric speed control device, for an engine having a fluid supply, an engine speed responsive mechanism including a movable speed responsive valve fed from said supply, a chamber, having a member movable therein, fed with fluid controlled by said valve, the position of said member being responsive to engine speed, an electrical switch contact movable with said member, a second switch contact engageable at times with the first, one of said contacts being resiliently mounted, and means for cyclically moving said second contact toward and away from the first contact, driven from the engine, said contacts being cyclically engageable with one another when said first contact is within the range of movement of said second contact, the duration of said engagements being a functionoi the position of said member and first contact and the cyclic rate of said second contact.

4. In a hydro-electric speed control device for use with an engine, a fluid supply, an engine driven rotating flywelght governor assembly, a valve movable along the axis about which the flyweights rotate in response to flyweight position changes, a fluid chamber fed by said fluid supply through said valve, a member movable in said chamber in accor dance with changes in the amount of fluid therein. an electrical switch point movable with said movable member, a second switch point, engageable at times with the first, mounted for movement, and engine operated means for cyclically moving said second point REFERENCES CITED The following references are of record in the file of this patent? UNITED STATES PATENTS Number Name Date 770,378 Mehrten Sept. 20, 1904 1,810,627 Standerwich June 16, 1931 1,953,790 Warren Apr. 3, 1934 2,032,255 Caldwell Feb. 25, 1936 2,112,251 Piau Mar. 29, 1938 2,246,516 Herzog June 24, 1941 2,258,462 Martin Oct. 7, 1941 

